Chronic inflammatory demyelinating polyneuropathy (hereinafter, also referred to as CIDP) is a peripheral nerve disease which features chronic progressive, chronic stepped or recurrent bilateral muscle weakness and sensation disturbance over 2 months or more in distal or proximal muscles of extremities as cardinal symptoms. The pathogenesis of CIDP is thought to be an autoimmune disease caused by immune abnormality to the constituent components of peripheral nerve myelin, details of which are not yet known.
At present, the guidelines proposed by the European Federation of Neurological Societies Peripheral Nerve Society (EFNSPNS) revised in 2010 are often used for the diagnosis of CIDP which has been carried out based on comprehensive judgment of clinical symptoms, electrophysiological criteria, cerebrospinal fluid findings, nerve root hypertrophy on MRI, and the like.
On the other hand, CIDP disease-specific biomarkers have not been reported to date. In addition, autoantibody-positive neuropathy for myelin-associated glycoprotein (MAG) is regarded as an independent disease, and it is excluded from CIDP.
CIDP is assumed to be a syndrome involving various pathological conditions since the progress, response to therapy and prognosis vary from case to case, and there is an urgent need in the art to establish a therapeutic regimen according to each pathological condition of CIDP.
The present inventors have found that the serum from the case of combined central and peripheral demyelination (CCPD), which is a rare disease causing demyelination in both the central nervous system and the peripheral nervous system, is positive for an anti-neurofascin 155 (NF155) antibody (Non-Patent Document 1). It has also been reported that the anti-NF155 antibody is positive in a small portion (about 4%) of CIDP (Non-Patent Documents 2 and 3).
However, the above reports are merely a small number of studies and no comparison between antibody-positive CIDP and antibody-negative CIDP has been made. For these reasons, it was unknown whether or not a specific subtype in CIDP becomes positive, and whether or not such a specific subtype in CIDP is associated with the clinical feature.